Chorea

Description

Chorea is a hyperkinetic movement disorder consisting of involuntary movements that are rapid, nonpatterned, and flow from one body part to another, often involving the distal limbs but also potentially involving the face and trunk.

In terms of distinction from other movement phenotypes:

▪ The greater rapidity distinguishes it from athetosis, which consists of slower, continuous, writhing movements.
▪ The nonpatterned nature (random, unpredictable) distinguishes it from tremor ➚ , in that it is irregular and unpredictable in timing, speed and direction.
▪ The nonpatterned, flowing quality distinguishes it from dystonia ➚ , which produces patterned movements and/or abnormal postures.
▪ The typically smaller-amplitude and more distal distribution distinguishes it from ballism, which is characterised by large-amplitude, predominantly proximal movements.

Chorea may be considered along a spectrum of hyperkinetic movements that includes athetosis and ballism.

▪ Athetosis also typically involves the distal extremities and consists of slower, continuous, writhing movements. These movements can cooccur with those of chorea; a pattern called choreoathetosis.
▪ Ballism, by contrast, tends to involve the proximal extremities with large-amplitude involuntary movements, often unilateral (hemiballism), resembling flinging of the upper limb or kicking with the lower limb.

Initial considerations

Huntington disease is an important diagnosis to consider in adults presenting with chorea, as it is the most common cause of chronic progressive chorea in adults and the most common hereditary cause of chorea. Other hereditary neurodegenerative disorders can produce similar clinical presentations. Acquired causes of chorea, including cerebrovascular disease, autoimmune disorders, and medications, should also be considered, particularly when the onset is acute or subacute, the clinical features are atypical, or there are other neurologic or systemic features suggesting an alternative diagnosis.

Although this section is primarily concerned with chronic chorea in adults, clinicians should remain vigilant for acute or sudden-onset chorea, particularly hemichorea, which may represent a medical emergency and therefore requires prompt assessment. Cerebrovascular disease, including basal ganglia ischemic or hemorrhagic stroke, is an important consideration, as are other potentially treatable causes such as non-ketotic hyperglycemia.